From d5de680e20def848751cb3c11e1182408112b1d3 Mon Sep 17 00:00:00 2001 From: Yilin Chen Date: Fri, 17 Sep 2021 20:21:33 +0800 Subject: [PATCH] Work around invalid DWARF bugs for fat LTO Signed-off-by: Yilin Chen --- compiler/rustc_codegen_llvm/src/back/lto.rs | 18 ++++++++++++++++-- compiler/rustc_codegen_llvm/src/llvm/ffi.rs | 8 ++------ .../rustc_llvm/llvm-wrapper/PassWrapper.cpp | 4 ++-- 3 files changed, 20 insertions(+), 10 deletions(-) diff --git a/compiler/rustc_codegen_llvm/src/back/lto.rs b/compiler/rustc_codegen_llvm/src/back/lto.rs index f612785e5a416..99b30264d0958 100644 --- a/compiler/rustc_codegen_llvm/src/back/lto.rs +++ b/compiler/rustc_codegen_llvm/src/back/lto.rs @@ -325,6 +325,20 @@ fn fat_lto( drop(linker); save_temp_bitcode(&cgcx, &module, "lto.input"); + // Fat LTO also suffers from the invalid DWARF issue similar to Thin LTO. + // Here we rewrite all `DICompileUnit` pointers if there is only one `DICompileUnit`. + // This only works around the problem when codegen-units = 1. + // Refer to the comments in the `optimize_thin_module` function for more details. + let mut cu1 = ptr::null_mut(); + let mut cu2 = ptr::null_mut(); + unsafe { llvm::LLVMRustLTOGetDICompileUnit(llmod, &mut cu1, &mut cu2) }; + if !cu2.is_null() { + let _timer = + cgcx.prof.generic_activity_with_arg("LLVM_fat_lto_patch_debuginfo", &*module.name); + unsafe { llvm::LLVMRustLTOPatchDICompileUnit(llmod, cu1) }; + save_temp_bitcode(cgcx, &module, "fat-lto-after-patch"); + } + // Internalize everything below threshold to help strip out more modules and such. unsafe { let ptr = symbols_below_threshold.as_ptr(); @@ -748,7 +762,7 @@ pub unsafe fn optimize_thin_module( // an error. let mut cu1 = ptr::null_mut(); let mut cu2 = ptr::null_mut(); - llvm::LLVMRustThinLTOGetDICompileUnit(llmod, &mut cu1, &mut cu2); + llvm::LLVMRustLTOGetDICompileUnit(llmod, &mut cu1, &mut cu2); if !cu2.is_null() { let msg = "multiple source DICompileUnits found"; return Err(write::llvm_err(&diag_handler, msg)); @@ -847,7 +861,7 @@ pub unsafe fn optimize_thin_module( let _timer = cgcx .prof .generic_activity_with_arg("LLVM_thin_lto_patch_debuginfo", thin_module.name()); - llvm::LLVMRustThinLTOPatchDICompileUnit(llmod, cu1); + llvm::LLVMRustLTOPatchDICompileUnit(llmod, cu1); save_temp_bitcode(cgcx, &module, "thin-lto-after-patch"); } diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs index 3f2ed02d90df3..d8c2a345fb03c 100644 --- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs +++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs @@ -2377,12 +2377,8 @@ extern "C" { len: usize, out_len: &mut usize, ) -> *const u8; - pub fn LLVMRustThinLTOGetDICompileUnit( - M: &Module, - CU1: &mut *mut c_void, - CU2: &mut *mut c_void, - ); - pub fn LLVMRustThinLTOPatchDICompileUnit(M: &Module, CU: *mut c_void); + pub fn LLVMRustLTOGetDICompileUnit(M: &Module, CU1: &mut *mut c_void, CU2: &mut *mut c_void); + pub fn LLVMRustLTOPatchDICompileUnit(M: &Module, CU: *mut c_void); pub fn LLVMRustLinkerNew(M: &'a Module) -> &'a mut Linker<'a>; pub fn LLVMRustLinkerAdd( diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp index b7cad1c3ba6d9..9061119360464 100644 --- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp +++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp @@ -1740,7 +1740,7 @@ LLVMRustGetBitcodeSliceFromObjectData(const char *data, // Rewrite all `DICompileUnit` pointers to the `DICompileUnit` specified. See // the comment in `back/lto.rs` for why this exists. extern "C" void -LLVMRustThinLTOGetDICompileUnit(LLVMModuleRef Mod, +LLVMRustLTOGetDICompileUnit(LLVMModuleRef Mod, DICompileUnit **A, DICompileUnit **B) { Module *M = unwrap(Mod); @@ -1758,7 +1758,7 @@ LLVMRustThinLTOGetDICompileUnit(LLVMModuleRef Mod, // Rewrite all `DICompileUnit` pointers to the `DICompileUnit` specified. See // the comment in `back/lto.rs` for why this exists. extern "C" void -LLVMRustThinLTOPatchDICompileUnit(LLVMModuleRef Mod, DICompileUnit *Unit) { +LLVMRustLTOPatchDICompileUnit(LLVMModuleRef Mod, DICompileUnit *Unit) { Module *M = unwrap(Mod); // If the original source module didn't have a `DICompileUnit` then try to